Move ExoPlayer initialization to a Dagger module and optimize its dependencies (#4296)

Currently, ExoPlayer is initialized explicitly in `ViewMediaFragment`
with all its dependencies, including many that are not useful for
viewing Mastodon media attachments.

This pull request moves most ExoPlayer initialization and configuration
to a new Dagger module, and instead a `Provider<ExoPlayer>` factory is
injected in the Fragment so it can create new instances when needed.

The following ExoPlayer components will be configured:

- **Renderers**: all of them (audio, video, metadata, subtitles) except
for the `CameraMotionRenderer`.
- **Extractors**: FLAC, Wav, Mp4, Ogg, Matroska/WebM and MP3 containers,
to provide the same support as Firefox or Chrome browsers. Other
container formats that are either image formats (already covered by
Glide), not web-friendly or reserved for live streaming are skipped.
- **MediaSource**: only progressive download (through OkHttp) is
provided. Live streaming support using protocols like RTSP, MPEG/Dash or
HLS is skipped, because Mastodon servers don't use these protocols to
download attachments.

The Mastodon documentation mentions the [supported media formats for
attachments](https://docs.joinmastodon.org/user/posting/#media) and this
covers them and even more. The docs also mentions that the video and
audio files are transcoded to MP4 and MP3 upon upload but that was not
the case in the past (for example WebM was used) and it could change
again in the future.

Specifying these components manually allows reducing the APK size by
about 200 KB thanks to R8 shrinking.

There are also a few extra code changes:
- Remove the code specific to API < 24 since the min SDK of the app is
now 24.
- Add support for pausing a video when unplugging headphones.
- Specify the audio attributes according to content type to help the
Android audio mixer.

app/src/main/java/com/keylesspalace/tusky/di/AppComponent.kt

@@ -36,7 +36,8 @@ import javax.inject.Singleton
         ServicesModule::class,
         BroadcastReceiverModule::class,
         ViewModelModule::class,
-        WorkerModule::class
+        WorkerModule::class,
+        PlayerModule::class
     ]
 )
 interface AppComponent {

app/src/main/java/com/keylesspalace/tusky/di/PlayerModule.kt

@@ -0,0 +1,139 @@
+/*
+ * Copyright 2024 Tusky Contributors
+ *
+ * This file is a part of Tusky.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Tusky; if not,
+ * see <http://www.gnu.org/licenses>.
+ */
+
+package com.keylesspalace.tusky.di
+
+import android.content.Context
+import android.os.Looper
+import androidx.annotation.OptIn
+import androidx.media3.common.C
+import androidx.media3.common.util.UnstableApi
+import androidx.media3.datasource.DataSource
+import androidx.media3.datasource.DefaultDataSource
+import androidx.media3.datasource.okhttp.OkHttpDataSource
+import androidx.media3.exoplayer.DefaultRenderersFactory
+import androidx.media3.exoplayer.ExoPlayer
+import androidx.media3.exoplayer.RenderersFactory
+import androidx.media3.exoplayer.audio.AudioSink
+import androidx.media3.exoplayer.audio.DefaultAudioSink
+import androidx.media3.exoplayer.audio.MediaCodecAudioRenderer
+import androidx.media3.exoplayer.mediacodec.MediaCodecSelector
+import androidx.media3.exoplayer.metadata.MetadataRenderer
+import androidx.media3.exoplayer.source.MediaSource
+import androidx.media3.exoplayer.source.ProgressiveMediaSource
+import androidx.media3.exoplayer.text.TextRenderer
+import androidx.media3.exoplayer.video.MediaCodecVideoRenderer
+import androidx.media3.extractor.ExtractorsFactory
+import androidx.media3.extractor.flac.FlacExtractor
+import androidx.media3.extractor.mkv.MatroskaExtractor
+import androidx.media3.extractor.mp3.Mp3Extractor
+import androidx.media3.extractor.mp4.FragmentedMp4Extractor
+import androidx.media3.extractor.mp4.Mp4Extractor
+import androidx.media3.extractor.ogg.OggExtractor
+import androidx.media3.extractor.wav.WavExtractor
+import dagger.Module
+import dagger.Provides
+import okhttp3.OkHttpClient
+
+@Module
+@OptIn(UnstableApi::class)
+object PlayerModule {
+    @Provides
+    fun provideAudioSink(context: Context): AudioSink {
+        return DefaultAudioSink.Builder(context)
+            .build()
+    }
+
+    @Provides
+    fun provideRenderersFactory(context: Context, audioSink: AudioSink): RenderersFactory {
+        return RenderersFactory { eventHandler,
+                                  videoRendererEventListener,
+                                  audioRendererEventListener,
+                                  textRendererOutput,
+                                  metadataRendererOutput ->
+            arrayOf(
+                MediaCodecVideoRenderer(
+                    context,
+                    MediaCodecSelector.DEFAULT,
+                    DefaultRenderersFactory.DEFAULT_ALLOWED_VIDEO_JOINING_TIME_MS,
+                    eventHandler,
+                    videoRendererEventListener,
+                    DefaultRenderersFactory.MAX_DROPPED_VIDEO_FRAME_COUNT_TO_NOTIFY
+                ),
+                MediaCodecAudioRenderer(
+                    context,
+                    MediaCodecSelector.DEFAULT,
+                    eventHandler,
+                    audioRendererEventListener,
+                    audioSink
+                ),
+                TextRenderer(
+                    textRendererOutput,
+                    eventHandler.looper
+                ),
+                MetadataRenderer(
+                    metadataRendererOutput,
+                    eventHandler.looper
+                )
+            )
+        }
+    }
+
+    @Provides
+    fun provideExtractorsFactory(): ExtractorsFactory {
+        // Extractors order is optimized according to
+        // https://docs.google.com/document/d/1w2mKaWMxfz2Ei8-LdxqbPs1VLe_oudB-eryXXw9OvQQ
+        return ExtractorsFactory {
+            arrayOf(
+                FlacExtractor(),
+                WavExtractor(),
+                Mp4Extractor(),
+                FragmentedMp4Extractor(),
+                OggExtractor(),
+                MatroskaExtractor(),
+                Mp3Extractor()
+            )
+        }
+    }
+
+    @Provides
+    fun provideDataSourceFactory(context: Context, okHttpClient: OkHttpClient): DataSource.Factory {
+        return DefaultDataSource.Factory(context, OkHttpDataSource.Factory(okHttpClient))
+    }
+
+    @Provides
+    fun provideMediaSourceFactory(
+        dataSourceFactory: DataSource.Factory,
+        extractorsFactory: ExtractorsFactory
+    ): MediaSource.Factory {
+        // Only progressive download is supported for Mastodon attachments
+        return ProgressiveMediaSource.Factory(dataSourceFactory, extractorsFactory)
+    }
+
+    @Provides
+    fun provideExoPlayer(
+        context: Context,
+        renderersFactory: RenderersFactory,
+        mediaSourceFactory: MediaSource.Factory
+    ): ExoPlayer {
+        return ExoPlayer.Builder(context, renderersFactory, mediaSourceFactory)
+            .setLooper(Looper.getMainLooper())
+            .setHandleAudioBecomingNoisy(true) // automatically pause when unplugging headphones
+            .setWakeMode(C.WAKE_MODE_NONE) // playback is always in the foreground
+            .build()
+    }
+}

app/src/main/java/com/keylesspalace/tusky/fragment/ViewMediaFragment.kt

@@ -17,9 +17,7 @@ package com.keylesspalace.tusky.fragment
 
 import android.os.Bundle
 import android.text.TextUtils
-import androidx.annotation.OptIn
 import androidx.fragment.app.Fragment
-import androidx.media3.common.util.UnstableApi
 import com.keylesspalace.tusky.ViewMediaActivity
 import com.keylesspalace.tusky.entity.Attachment
 
@@ -49,7 +47,6 @@ abstract class ViewMediaFragment : Fragment() {
         protected val ARG_SINGLE_IMAGE_URL = "singleImageUrl"
 
         @JvmStatic
-        @OptIn(UnstableApi::class)
         fun newInstance(
             attachment: Attachment,
             shouldStartPostponedTransition: Boolean

app/src/main/java/com/keylesspalace/tusky/fragment/ViewVideoFragment.kt

@@ -20,7 +20,6 @@ import android.animation.AnimatorListenerAdapter
 import android.annotation.SuppressLint
 import android.content.Context
 import android.graphics.drawable.Drawable
-import android.os.Build
 import android.os.Bundle
 import android.os.Handler
 import android.os.Looper
@@ -35,14 +34,13 @@ import android.widget.FrameLayout
 import android.widget.LinearLayout
 import androidx.annotation.OptIn
 import androidx.core.view.GestureDetectorCompat
+import androidx.media3.common.AudioAttributes
+import androidx.media3.common.C
 import androidx.media3.common.MediaItem
 import androidx.media3.common.PlaybackException
 import androidx.media3.common.Player
 import androidx.media3.common.util.UnstableApi
-import androidx.media3.datasource.DefaultDataSource
-import androidx.media3.datasource.okhttp.OkHttpDataSource
 import androidx.media3.exoplayer.ExoPlayer
-import androidx.media3.exoplayer.source.DefaultMediaSourceFactory
 import androidx.media3.exoplayer.util.EventLogger
 import androidx.media3.ui.AspectRatioFrameLayout
 import com.bumptech.glide.Glide
@@ -59,17 +57,17 @@ import com.keylesspalace.tusky.util.hide
 import com.keylesspalace.tusky.util.viewBinding
 import com.keylesspalace.tusky.util.visible
 import javax.inject.Inject
+import javax.inject.Provider
 import kotlin.math.abs
-import okhttp3.OkHttpClient
 
-@UnstableApi
+@OptIn(UnstableApi::class)
 class ViewVideoFragment : ViewMediaFragment(), Injectable {
     interface VideoActionsListener {
         fun onDismiss()
     }
 
     @Inject
-    lateinit var okHttpClient: OkHttpClient
+    lateinit var playerProvider: Provider<ExoPlayer>
 
     private val binding by viewBinding(FragmentViewVideoBinding::bind)
 
@@ -92,8 +90,6 @@ class ViewVideoFragment : ViewMediaFragment(), Injectable {
     /** The saved seek position, if the fragment is being resumed */
     private var savedSeekPosition: Long = 0
 
-    private lateinit var mediaSourceFactory: DefaultMediaSourceFactory
-
     /** Have we received at least one "READY" event? */
     private var haveStarted = false
 
@@ -106,9 +102,6 @@ class ViewVideoFragment : ViewMediaFragment(), Injectable {
     override fun onAttach(context: Context) {
         super.onAttach(context)
 
-        mediaSourceFactory = DefaultMediaSourceFactory(context)
-            .setDataSourceFactory(DefaultDataSource.Factory(context, OkHttpDataSource.Factory(okHttpClient)))
-
         videoActionsListener = context as VideoActionsListener
     }
 
@@ -285,53 +278,18 @@ class ViewVideoFragment : ViewMediaFragment(), Injectable {
 
     override fun onStart() {
         super.onStart()
-        if (Build.VERSION.SDK_INT > 23) {
-            initializePlayer()
-            binding.videoView.onResume()
-        }
-    }
 
-    override fun onResume() {
+        initializePlayer()
-        super.onResume()
+        binding.videoView.onResume()
-
-        if (Build.VERSION.SDK_INT <= 23 || player == null) {
-            initializePlayer()
-
-            binding.videoView.onResume()
-        }
-    }
-
-    private fun releasePlayer() {
-        player?.let {
-            savedSeekPosition = it.currentPosition
-            it.release()
-            player = null
-            binding.videoView.player = null
-        }
-    }
-
-    override fun onPause() {
-        super.onPause()
-
-        // If <= API 23 then multi-window mode is not available, so this is a good time to
-        // pause everything
-        if (Build.VERSION.SDK_INT <= 23) {
-            binding.videoView.onPause()
-            releasePlayer()
-            handler.removeCallbacks(hideToolbar)
-        }
     }
 
     override fun onStop() {
         super.onStop()
 
-        // If > API 23 then this might be multi-window, and definitely wasn't paused in onPause,
+        // This might be multi-window, so pause everything now.
-        // so pause everything now.
+        binding.videoView.onPause()
-        if (Build.VERSION.SDK_INT > 23) {
+        releasePlayer()
-            binding.videoView.onPause()
+        handler.removeCallbacks(hideToolbar)
-            releasePlayer()
-            handler.removeCallbacks(hideToolbar)
-        }
     }
 
     override fun onSaveInstanceState(outState: Bundle) {
@@ -340,18 +298,22 @@ class ViewVideoFragment : ViewMediaFragment(), Injectable {
     }
 
     private fun initializePlayer() {
-        ExoPlayer.Builder(requireContext())
+        player = playerProvider.get().apply {
-            .setMediaSourceFactory(mediaSourceFactory)
+            setAudioAttributes(
-            .build().apply {
+                AudioAttributes.Builder()
-                if (BuildConfig.DEBUG) addAnalyticsListener(EventLogger("$TAG:ExoPlayer"))
+                    .setContentType(if (isAudio) C.AUDIO_CONTENT_TYPE_UNKNOWN else C.AUDIO_CONTENT_TYPE_MOVIE)
-                setMediaItem(MediaItem.fromUri(mediaAttachment.url))
+                    .setUsage(C.USAGE_MEDIA)
-                addListener(mediaPlayerListener)
+                    .build(),
-                repeatMode = Player.REPEAT_MODE_ONE
+                true
-                playWhenReady = true
+            )
-                seekTo(savedSeekPosition)
+            if (BuildConfig.DEBUG) addAnalyticsListener(EventLogger("$TAG:ExoPlayer"))
-                prepare()
+            setMediaItem(MediaItem.fromUri(mediaAttachment.url))
-                player = this
+            addListener(mediaPlayerListener)
-            }
+            repeatMode = Player.REPEAT_MODE_ONE
+            playWhenReady = true
+            seekTo(savedSeekPosition)
+            prepare()
+        }
 
         binding.videoView.player = player
 
@@ -378,6 +340,15 @@ class ViewVideoFragment : ViewMediaFragment(), Injectable {
         }
     }
 
+    private fun releasePlayer() {
+        player?.let {
+            savedSeekPosition = it.currentPosition
+            it.release()
+            player = null
+            binding.videoView.player = null
+        }
+    }
+
     @SuppressLint("ClickableViewAccessibility")
     override fun setupMediaView(
         url: String,

gradle/libs.versions.toml

@@ -79,9 +79,6 @@ androidx-lifecycle-livedata-ktx = { module = "androidx.lifecycle:lifecycle-lived
 androidx-lifecycle-reactivestreams-ktx = { module = "androidx.lifecycle:lifecycle-reactivestreams-ktx", version.ref = "androidx-lifecycle" }
 androidx-lifecycle-viewmodel-ktx = { module = "androidx.lifecycle:lifecycle-viewmodel-ktx", version.ref = "androidx-lifecycle" }
 androidx-media3-exoplayer = { module = "androidx.media3:media3-exoplayer", version.ref = "androidx-media3" }
-androidx-media3-exoplayer-dash = { module = "androidx.media3:media3-exoplayer-dash", version.ref = "androidx-media3" }
-androidx-media3-exoplayer-hls = { module = "androidx.media3:media3-exoplayer-hls", version.ref = "androidx-media3" }
-androidx-media3-exoplayer-rtsp = { module = "androidx.media3:media3-exoplayer-rtsp", version.ref = "androidx-media3" }
 androidx-media3-datasource-okhttp = { module = "androidx.media3:media3-datasource-okhttp", version.ref = "androidx-media3" }
 androidx-media3-ui = { module = "androidx.media3:media3-ui", version.ref = "androidx-media3" }
 androidx-paging-runtime-ktx = { module = "androidx.paging:paging-runtime-ktx", version.ref = "androidx-paging" }
@@ -142,8 +139,8 @@ androidx = ["androidx-core-ktx", "androidx-appcompat", "androidx-fragment-ktx",
     "androidx-emoji2-core", "androidx-emoji2-views-core", "androidx-emoji2-view-helper", "androidx-lifecycle-viewmodel-ktx",
     "androidx-lifecycle-livedata-ktx", "androidx-lifecycle-common-java8", "androidx-lifecycle-reactivestreams-ktx",
     "androidx-constraintlayout", "androidx-paging-runtime-ktx", "androidx-viewpager2", "androidx-work-runtime-ktx",
-    "androidx-core-splashscreen", "androidx-activity", "androidx-media3-exoplayer", "androidx-media3-exoplayer-dash",
+    "androidx-core-splashscreen", "androidx-activity", "androidx-media3-exoplayer", "androidx-media3-datasource-okhttp",
-    "androidx-media3-exoplayer-hls", "androidx-media3-exoplayer-rtsp", "androidx-media3-datasource-okhttp", "androidx-media3-ui"]
+    "androidx-media3-ui"]
 dagger = ["dagger-core", "dagger-android-core", "dagger-android-support"]
 dagger-processors = ["dagger-compiler", "dagger-android-processor"]
 filemojicompat = ["filemojicompat-core", "filemojicompat-ui", "filemojicompat-defaults"]